2013. US Environmental Protection Agency. Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources. They are designed to... U.S. EPA Office of Research & Development (ORD) - National Health and Environmental Effects Research Laboratory (NHEERL).
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1993. Arizona. State Land Department. This statewide data set includes Bureau of Land Management, U.S. Forest Service, National Park Service and Fish & Wildlife Service Riparian Natural... Arizona State Land Department.